U.S. patent number 4,803,340 [Application Number 07/040,343] was granted by the patent office on 1989-02-07 for covered arc-welding electrode.
This patent grant is currently assigned to Kawasaki Steel Corp.. Invention is credited to Junya Matsuyama, Noboru Nishiyama, Kouki Sato.
United States Patent |
4,803,340 |
Sato , et al. |
February 7, 1989 |
**Please see images for:
( Certificate of Correction ) ** |
Covered arc-welding electrode
Abstract
A covered arc welding electrode includes a steel core wire and a
flux which is applied to the outside periphery of said steel core
wire. The welding electrode can form a superior crack-resisting
weld zone even if fluctuating stresses are continually applied to a
base metal while the base metal is welded. The flux includes 40 to
60% metal carbonate, 10 to 25% metal fluoride and 4 to 25 metal
oxide by weight. The flux comprises 24 to 32% of the total weight
of said electrode. The composition of the welding electrode
includes 0.005 to 0.05% carbon, 0.1 to 1.1% silicon, 1.5 to 2.5%
manganese, not more than 0.007% sulfur and not more than 0.25%
nickel by weight and the manganese/sulfur ratio is more than or
equal to 350 to 1. In addition, the welding electrode can include
0.01 to 0.10% rare earth metal by weight. In which case, the Mn
content may be 1.0 to 2.5% by weight and the manganese/sulfur ratio
may be more than or equal to 270 to 1. In addition, the composition
of the welding electrode can include titanium and zirconium, the
total content of which may be less than or equal to 1.2% the total
weight of the electrode, and/or aluminum and magnesium, the total
content of which may be less than or equal to 1.2% of the total
weight of the electrode.
Inventors: |
Sato; Kouki (Chiba,
JP), Matsuyama; Junya (Chiba, JP),
Nishiyama; Noboru (Chiba, JP) |
Assignee: |
Kawasaki Steel Corp. (Hyogo,
JP)
|
Family
ID: |
26433721 |
Appl.
No.: |
07/040,343 |
Filed: |
April 20, 1987 |
Foreign Application Priority Data
|
|
|
|
|
Apr 23, 1986 [JP] |
|
|
61-92269 |
Jul 25, 1986 [JP] |
|
|
61-173574 |
|
Current U.S.
Class: |
219/146.1;
219/145.23 |
Current CPC
Class: |
B23K
35/3073 (20130101); B23K 35/3602 (20130101) |
Current International
Class: |
B23K
35/36 (20060101); B23K 35/30 (20060101); B23K
035/22 () |
Field of
Search: |
;219/146.1,146.24,146.41,145.23,146.23,146.52 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
2900490 |
August 1959 |
Petryck et al. |
4091147 |
May 1978 |
Kanazawa et al. |
4251711 |
February 1981 |
Tanigaki et al. |
|
Foreign Patent Documents
Primary Examiner: Goldberg; E. A.
Assistant Examiner: Walberg; Teresa J.
Attorney, Agent or Firm: Miller; Austin R.
Claims
What is claimed is:
1. A covered arc welding electrode comprising:
a flux including 40 to 60% metal carbonate, 10 to 25% metal
fluoride and 4 to 25% metal oxide by weight; and
a steel core wire, onto the outer periphery of which said flux is
applied so as to comprise 24 to 32% of the total weight of said
electrode,
said electrode as a whole being comprised of 0.005 to 0.05% carbon,
0.1 to 1.1% silicon, 1.5 to 2.5% manganese, not more than 0.007%
sulfur and not more than 0.25% nickel by weight and in which the
manganese/sulfur ratio is more than or equal to 350 to 1.
2. A covered arc-welding electrode as set forth in claim 1, further
comprising titanium and zirconium, the total content of which is
less than or equal to 1.2% of the total weight of the
electrode.
3. A covered arc-welding electrode as set forth in claim 2, further
comprising aluminum and magnesium, the total content of which is
less than or equal to 1.2% of the total weight of the
electrode.
4. A covered arc-welding electrode as set forth in claim 1, further
comprising aluminum and magnesium, the total content of which is
less than or equal to 1.2% of the total weight of the
electrode.
5. A covered arc-welding electrode comprising:
a flux including by weight 40 to 60% metal carbonate, 10 to 25%
metal fluoride and 4 to 25% metal oxide; and
a steel core wire, onto the outer periphery of which said flux is
applied so as to comprise 24 to 32% of the total weight of said
electrode;
said electrode as a whole being comprised of 0.005 to 0.05% carbon,
0.1 to 1.1% silicon, 1.0 to 2.5% manganese, not more than 0.007%
sulfur, not more than 0.25% nickel and 0.01 to 0.10% rare earth
metal by weight and in which the manganese/sulfur ratio is more
than or equal to 270 to 1.
6. A covered arc-welding electrode as set forth in claim 5, further
comprising titanium and zirconium, the total content of which is
less than or equal to 1.2% of the total weight of the
electrode.
7. A covered arc-welding electrode as set forth in claim 6, further
comprising aluminum and magnesium, the total content of which is
less than or equal to 1.2% of the total weight of the
electrode.
8. A covered arc-welding electrode as set forth in claim 5, further
comprising aluminum and magnesium, the total content of which is
less than or equal to 1.2% of the total weight of the electrode.
Description
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a covered arc welding electrode.
More specifically, the invention relates to a covered arc-welding
electrode which can form a superior crack-resisting weld zone even
if a base metal, such as an established steel bridge, an ocean
structure or the like, is welded while fluctuating stresses are
continually applied to the base metal.
2. DESCRIPTION OF THE PRIOR ART
While vehicles and so forth pass over a bridge, fluctuating
stresses are continually applied thereto. When welding a structure
under operating conditions for repair or rebuilding, small cracks
are often generated immediately after welding it since tension and
compression are continually applied thereto while the weld metal is
still at a high temperature and is therefore brittle. Afterward,
these small cracks can serve as the starting points from which
larger cracks may grow and cause the life of the bridge to become
shorter.
When conventional covered arc welding electrodes are used, traffic
on the bridge or the like must be restricted while welding is
performed or the weld zone must somehow be stationarily fixed prior
to welding. Otherwise, unless other fastening means are employed,
the generation of cracks is considered to be inevitable and a
shortened functioning life of the structure must be
anticipated.
SUMMARY OF THE INVENTION
It is therefore a principle object of the present invention to
eliminate the aforementioned disadvantage and to provide a covered
arc-welding electrode which can form a superior crack-resisting
weld zone even if the base metal is welded while fluctuating
stresses are continually applied.
In order to accomplish the aforementioned and other specific
objects, a covered arc-welding electrode according to the present
invention includes a steel core wire and a flux which is formed
onto the outside periphery of the steel core wire.
According to one preferred construction of the present invention,
the flux is comprised of 40 to 60% by weight metal carbonate, 10 to
25% by weight metal fluoride and 4 to 25% by weight metal oxide.
The flux comprises 24 to 32% of the total weight of said electrode.
By weight the welding electrode is comprised of 0.005 to 0.05%
carbon, 0.1 to 1.1% silicon, 1.5 to 2.5% manganese, not more than
0.007% sulfur and not more than 0.25% nickel, in which the
manganese/sulfur ratio of the electrode is more than or equal to
350 to 1. In addition, the welding electrode can include titanium
and zirconium, which may comprise not more than 1.2 % of the total
weight of the electrode, and/or aluminum and magnesium, which may
comprise not more than 1.2 % of the total weight of the
electrode.
According to another preferred construction of the invention, the
welding electrode includes a rare earth metal (REM). By weight, the
flux is comprised of 40 to 60% metal carbonate, 10 to 25% metal
fluoride and 4 to 25% metal oxide. The flux comprises 24 to 32% of
the total weight of said electrode and is formed to the steel core
wire. By weight the welding electrode is comprised of 0.005 to
0.05% carbon, 0.1 to 1.1% silicon, 1.0 to 2.5% manganese, not more
than 0.007% sulfur, not more than 0.25% nickel and 0.01 to 0.10%
REM, in which the manganese/sulfur ratio of the electrode is more
than or equal to 270 to 1. In addition, the welding electrode can
include titanium and zirconium, which may comprise not than 1.2% of
the total weight of the electrode, and /or aluminum and magnesium,
which may comprises not more than 1.2% of the total weight of the
electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1(a) is a sectional view of a base metal which is welded by
means of a covered arc welding electrode.
FIG. 1(b) is a graph showing the displacement of the base metal
shown in FIG. 1(a) when fluctuating stresses are continually
applied to the base metal.
FIG. 2(a) is a perspective view of a test piece used in a variable
restraint test.
FIG. 2(b) is a perspective view of a test metal shown in FIG. 2(a),
the weld zone of which was welded by means of a covered arc welding
electrode of the invention and by means of a conventional or
compared covered arc welding electrode.
FIG. 3 is a plan view of a test piece which was used in a fatigue
test.
FIG. 4 is a longitudinal section of the test piece shown in FIG.
3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A covered arc welding electrode according to the present invention
has a superior crack-resisting. In the first preferred embodiment
of a covered arc-welding electrode of the invention, the flux
comprising 24 to 32% of the total weight of the electrode is formed
on the outer periphery of a steel core wire. By weight the flux is
comprised of 40 to 60% metal carbonate, 10 to 25% metal fluoride
and 4 to 25% metal oxide. By weight the welding electrode as a
whole is comprised of 0.005 to 0.05% C, 0.1 to 1.1% Si, 1.5 to 2.5%
Mn, not more than 0.007% S and not more than 0.25% Ni and the Mn/S
ratio of the welding electrode is more than or equal to 350 to 1.
In addition, the welding electrode may be comprised of not more
than 1.2% Ti and Zr and/or not more than 1.2% Al and Mg relative to
the total weight of the electrode.
The inventors have found that there is a close connection between
the formation of cracks and the melting point of non-metallic
inclusion formed during solidification. Particularly, it has been
found that among the chemical components of a welding electrode, S,
Mn, Si and C have the greatest influence upon the formation of
cracks.
More specifically, when the Mn/S ratio of a covered arc-welding
electrode is relatively small, low melting point inclusions, such
as Fe-FeS, are generated within the grain boundary of the bead. At
a high temperature, these inclusions decrease the ductility so as
to allow to cracks form therein. Furthermore, since the content of
Si in the covered arc-welding electrode is relatively high,
low-melting-point silicate inclusions, such as Si-Mn-O, are
generated which allow cracks to form therein on the aforementioned
grounds. In addition, carbon may easily becomes segregated during
the solidification process. Therefore, when the C content of the
welding electrode is relatively high, segregation occurs at the
grain boundary of the bead which allows cracks to form during the
solidification process.
With due consideration of the aforementioned points, the preferable
composition of a covered arc-welding electrode can be determined.
Furthermore, in addition to the abovementioned points, the
composition of a covered arc-welding electrode, according to the
present invention, was determined with the following reasons taken
into account.
In cases where less than 40% by weight of the flux is a metal
carbonate, the viscosity of a fused slag becomes high which
decreases efficiency with which welding work can be performed. In
addition, since shield gas is in short supply, blow holes are
generated in the bead. On the other hand, in cases where more than
60% by weight of the flux is a metal carbonate, the viscosity of
the fused metal is low causing the shape of bead to be uneven.
In cases where less than 10% by weight of the flux is a metal
fluoride, the viscosity of the fused slag is too high so that the
efficiency with which welding work can be performed is lowered. On
the other hand, when more than 25% by weight of the flux is a metal
fluoride, the viscosity of the fused slag is too low to allow the
the welding work to be performed effectively.
In cases where the flux comprises less than 24% by weight of the
covered arc-welding electrode, a sufficient guard cylinder can not
be formed. As a result, the amount of spattering is increased and
the shape of a bead is more uneven. On the other hand, when it is
more than 32% by weight, the amount of the slug is too much which
tends to deform the bead.
The mixing ratio of the indispensable elements comprising the
aforementioned electrode, i.e. the flux and the core wire, was
determined in accordance with the following considerations.
According to the invention, one of most important elements is
sulfur. If a large amount of sulfur is included in the composition
of the bead, then a great part thereof forms a sulphide inclusion
within the grain boundary of the metal. In particular, when
low-melting-point eutectic-crystal inclusions are formed, the
ductility of the weld metal is greatly decreased at a temperature
between the solidifying point of the weld metal and about
1000.degree. C. Preferably therefore, the very least amount of S is
preferably included. On the other hand, when the content of the S
is more than 0.007% by weight, it can be prevented from producing
low-melting-point FeS inclusions even if very large amounts of Mn,
Ti, Zr or the like are added as mentioned thereafter. Therefore,
the content of S is to be less than 0.007% by weight.
Another of most important elements is a manganese. Manganese
combines with S to form a high-melting-point MnS. Therefore, Mn is
an indispensable component for preventing generation of
low-melting-point FeS. If the Mn content is less than 1.5% by
weight, the aforementioned effect can not be achieved. On the other
hand, if the Mn content is more than 2.5%, quench hardening of the
weld metal is increased which tends to cause cracks to
generate.
The silicon acts as a deoxidizer. When the Si content is less than
0.1% by weight of the bead, the deoxidizer is in short supply
causing blow holes to be formed in the bead. On the other hand,
when the Si content is more than 1.1% by weight, low-melting-point
silicate-glass inclusions are generated in the bead causing the
ductility of the weld metal to be lowered.
Including a large amount of carbon in the bead has the effect of
preventing coarse ferrite deposits from occuring. Therefore, the
electrode must be comprised of at least 0.005% carbon by weight.
However, the C content must be less than 0.05% by weight since the
ductility of the weld metal at high temperatures is decreased when
the C content is too great.
Through Ni is one of the stable austenite former, Ni component is
not indispensable. However, when the amount of Ni is too great, Ni
tends to form S-segregation in the grain boundary. Therefore, the
content of the Ni should be less than 0.25% by weight.
In cases where the ratio Mn/S is less than 350 to 1, all of S can
not form MnS which is a high melting point inclusion and the rest
is deposited as FeS which is a low melting point inclusion so that
the ductility of the weld metal is decreased at high temperatures.
Therefore, the Mn/S ratio is preferably more than or equal to 350
to 1 in order to prevent cracks from occuring during welding
process is performed on the base metal under the fluctuating stress
in which the displacement is less than 20% when the root gap is 2
mm.
When the aforementioned components are included within the
aforementioned limits, the effect of the invention is comprised of
not more than 1.2% Ti and Zr by weight of and/or not more than 1.2%
Al and Mg by weight relative to the total weight of the electrode,
other desirable effects can be obtained.
Ti and Zr may be added to the electrode in order to serve as
supplementally deoxidizing agents in place of the decreased Si, to
nitrize and sulfurize the weld metal. Since the reactivity is
nitrization>sulfurization>carbonation, they are effective for
solidifying S, i.e. for preventing the ductility of the weld metal
from decreasing at high temperatures. However, when the Ti and Zr
more than 1.2% by weight are added to the welding electrode, the
precipitation of carbide is increased.
Al and Mg may be added to the welding electrode in order to
deoxidize the bead in place of the decreased Si. When 1.2% by
weight of Al and Mg are added to the welding electrode, the Si is
increased due to the reduction of the SiO.sub.2 included in the
flux so that the ductility of the bead is decreased at a high
temperature.
In second preferred embodiment of a covered arc-welding electrode
of the invention, 24 to 32% by weight of the total weight of the
electrode is flux formed on the outer periphery of the steel core
wire. By weight the flux includes 40 to 60% metal carbonate, 10 to
25% metal fluoride and 4 to 25% metal oxide. By weight the welding
electrode is comprised of 0.005 to 0.05% C, 0.1 to 1.1% Si, 1.0 to
2.5% Mn, not more than 0.007% S, not more than 0.25% Ni and 0.01 to
0.10% REM (Rare earth metal) and the Mn/S ratio in the welding
electrode is more than or equal to 270. In addition, the welding
electrode may include not more than 1.2% Ti and Zr and/or not more
than 1.2% Al and Mg relative to the total weight of the
electrode.
According to the aforementioned embodiment, 0.01 to 0.10% REM is
added to the welding electrode. The addition of the REM can broaden
the limits of the Mn content and the Mn/S ratio which can be
applied to the welding electrode. That is, the lower limits of the
Mn content of the welding electrode may be changed the limits from
1.5% of the total weight of the electrode to 1.0% thereof. In
addition, the Mn/S ratio of the electrode may be changed form more
than 350 to 1 to more than 270 to 1.
Since the REM tends to combine with S to generate high solidifying
point sulfides, low melting point inclusions do not tend to
precipitate in the grain boundary. Therefore, the ductility of the
bead is not decreased at high temperatures. However, when the REM
content is less than 0.01% by weight, such as effect can not be
achieved. On the other hand, when the REM content is more than
0.10% by weight, the ductility of the bead is lowered at ordinary
temperatures. In addition, although the REM may be added to the
flux, adding the REM to the core wire has proved to be a simpler
manufacturing process. The REM used for these experiments was a
mischmetal including 50% Ce.
EXAMPLE 1
In order to manufacture covered arc-welding electrodes according to
the first preferred embodiment of the invention, having the
compositions shown in Table 1, 24 to 32 wt. % flux was coated onto
the outer periphery of a steel core wire 4 mm in diameter. The
beveling of a steel plate shown in FIG. 2(a), the components of
which are shown in Table 3, were welded by means of the welding
electrode obtained to form a test piece shown in FIG. 2(b). With
respect to this test piece, a variable restraint test (varestraint
test) was carried out under a 4 to 15% of strain value.
As shown in Table 1 and 2, there are no cracks in the weld zones,
which were formed by means of covered arc-welding electrodes 2 to 8
according to the invention, under a 4 to 15% strain value.
On the other hand, when a conventional welding electrode 1 in which
the content of the C, Si, Mn and S and the Mn/S ratio are outside
the range of the invention, cracks were generated in the weld zone
even under a 4% of strain value.
For additional compositions, varestraint tests were carried out in
which welding electrodes 9 to 14 were used. The C, Si and S
contents and the Mn/S ratio of the welding electrode 9 are outside
the range of the invention. The Si content of the welding electrode
10 is outside the range of the invention. When the welding
electrodes 9 and 10 were used, cracks were generated under 4 or 10
to 15% of strain. In addition, the C, Si, Mn and Ni contents and
the Mn/S ratio of the welding electrode 11 are outside the range of
the invention. The C, Si, Mn and S contents and the Mn/S ratio of
the welding electrode 12 are outside the range of the invention.
The Si, Mn, S and Ni contents and the Mn/S ratio of the welding
electrode 13 and the C content of the welding electrode 14 are
outside the range of the invention. When the welding electrodes 11
to 14 were used, it was not possible to prevent cracks from
occuring under a 4 to 15% of strain.
In addition, a test piece shown in FIGS. 3 or 4 (b: 30 mm, c: 150
mm, d: 300 mm, e: 16 mm, .alpha.: 60.degree. in the drawings) was
subjected to a fatigue tests. The test piece was welded by means of
each of the welding electrodes of the invention under the nearly
same fluctuating stress as that found on an actual bridge, i.e.
under the fluctuation cycle shown in FIG. 1(b) with a .+-.0.2 mm
displacement value. A horizontal welding was made under the
following conditions; 170 Amp, 24 to 25 Volt and 15 cm per min.
Immediately after forming the weld, the test piece was cut into 10
cross sections. After the cross sections were polished, it was
observed whether or not cracks were generated in the bead. As a
result of these test, it was found that no crack was generated when
the welding electrodes 2 to 8 of the invention were used. On the
other hand, when the welding electrodes 1, 9 and 10, it was found
that many cracks were generated due to the insufficient ductility
of the bead at high temperatures.
EXAMPLE 2
In order to manufacture covered arc-welding electrodes according to
the second preferred embodiment of the invention, which has
component or composition shown in Table 4, 24 to 32% by weight of
flux was applied to the outer periphery of a steel core wire having
4 mm of diameter. The beveling portion of a steel plate shown in
FIG. 2(a), the component of which is shown in Table 3, was welded
by means of the welding electrode obtained to form a test piece
shown in FIG. 2(b). With respect to this test piece, a variable
restraint test (varestraint test) was carried out under 4 to 15% of
a strain value.
As shown in Table 4 and 5, there are no cracks in the weld zones,
which were formed by means of covered arc-welding electrodes 19 to
26 of the invention, under 4 to 15% of strain.
On the other hand, when a conventional welding electrode 15 in
which the C, Si, S and REM contents and the Mn/S ratio are outside
the range of the invention, cracks were generated in the weld zone
even under 4% of strain. When welding electrode 16 was used for
comparison, no crack was generated in the weld zone even under a
15% of strain since the composition and the Mn/S ratio thereof is
inside the range of the first preferred embodiment except for the
REM content. However, when welding electrodes 17 and 18 were used,
in which the content of the Mn was less than the lowest limit of
the first preferred embodiment of the invention and to which no REM
is applied, cracks were generated in the welded zone under more
than 4% of strain.
When welding electrode 27, in which the REM content is more than
the highest limit of the invention, was used, cracks were generated
in the weld zone under at more than 10% of strain.
In addition, the test piece shown in FIGS. 3 or 4 (b: 30 mm, c: 150
mm, d: 300 mm, e: 16 mm, .alpha.: 60.degree. in the drawings) was
set on a fatigue test apparatus. The test piece was welded by means
of each of the welding electrodes according to the second preferred
embodiment of the invention under the nearly same fluctuating
stress as that applied to an actual bridge, i.e. under the
fluctuating cycle shown in FIG. 1(b) and .+-.0.2 mm of a
displacement value. A horizontal welding was used under the
following conditions, 170 Amp, 24 to 25 Volt and 15 cm/min.
Immediately after welding, the test piece was cut in ten pieces to
expose its cross sections. After the cross sections were polished,
it was observed whether or not cracks were generated on the
surfaces. As a result of these test, it was observed that no crack
was generated in the pieces in which the welding electrodes 19 to
26 of the second preferred embodiment of the invention and the
welding electrode 16 of the first preferred embodiment of the
invention were used. On the other hand, when welding electrodes 15,
17 and 18 were used for comparison, it was observed that many
cracks were generated due to the beads lack of ductility at high
temperatures. In addition, when the welding electrode 27 was used,
small cracks were generated in the weld zone.
TABLE 1
__________________________________________________________________________
Compositions of Flux Wt. (%) Content in Electrode Wt. (%) K.sub.2 O
Covering Ti Al Na.sub.2 O The Ratio No. C Si Mn S Ni Zr Mg Mn/s
CaCO.sub.3 BaCO.sub.3 CaF.sub.2 SiO.sub.2 Al.sub.2 O.sub.3
TiO.sub.2 Li.sub.2 O Others (%)
__________________________________________________________________________
1 0.07 1.5 1.1 0.011 0.02 0.30 0.61 100 45 5 17 10 2 5 3 13 29 2
0.01 0.5 1.5 0.003 0.02 tr tr 500 45 3 16 10 3 5 4 14 29 3 0.05 0.5
1.6 0.002 0.01 tr tr 800 40 -- 10 14 3 4 4 25 24 4 0.005 0.1 2.5
0.007 0.01 0.38 0.25 357 51 5 16 10 5 2 3 8 29 5 0.03 1.1 1.9 0.003
0.05 tr 0.37 633 45 5 17 11 3 4 3 12 29 6 0.02 0.2 2.2 0.003 0.25
0.12 0.85 733 40 3 25 8 2 2 3 17 32 7 0.03 0.5 1.6 0.004 0.01 0.12
tr 400 45 3 16 10 3 5 4 14 29 8 0.04 0.5 1.6 0.004 0.01 tr tr 400
45 3 16 10 3 5 4 14 29 9 0.08 1.4 1.5 0.008 0.01 0.12 0.35 188 45 5
17 11 3 4 3 12 29 10 0.03 1.5 1.7 0.003 0.02 0.12 0.35 567 45 5 17
11 3 4 3 12 28 11 0.09 1.5 1.0 0.010 0.55 0.12 tr 100 48 3 16 10 2
4 4 13 28 12 0.10 1.6 1.0 0.012 0.01 0.15 0.16 83 50 -- 17 10 3 3 3
14 29 13 0.05 1.4 1.1 0.010 2.09 0.15 tr 150 45 3 16 10 3 5 4 14 29
14 0.10 0.5 1.6 0.004 0.02 0.24 0.21 140 45 3 16 11 3 5 4 13 29
__________________________________________________________________________
Notes: The others include Fe, C, Si, Mn, Ni, Al, Ti, Mg, Zr and so
forth.
TABLE 2 ______________________________________ Varestraint Test
Strain (%) No. 4 10 15 ______________________________________ 1 YES
YES YES 2 NO NO NO 3 NO NO NO 4 NO NO NO 5 NO NO NO 6 NO NO NO 7 NO
NO NO 8 NO NO NO 9 YES YES YES 10 NO YES YES 11 YES YES YES 12 YES
YES YES 13 YES YES YES 14 YES YES YES
______________________________________ YES: Cracks were generated.
NO: No Cracks
TABLE 3 ______________________________________ Chemical Component
(%) Steel C Si Mn P S Ni Cr Mo
______________________________________ SM58Q 0.11 0.24 1.70 0.017
0.003 0.02 0.01 tr ______________________________________
TABLE 4
__________________________________________________________________________
Content in Electrode Wt. (%) Composition of Flux Wt. (%) Cov- Ti Al
K.sub.2 O ering + + Na.sub.2 O The Ratio No. C Si Mn S Ni Zr Mg REM
Mn/s CaCO.sub.3 BaCO.sub.3 CaF.sub.2 SiO.sub.2 Al.sub.2 O.sub.3
TiO.sub.2 Li.sub.2 O Others (%)
__________________________________________________________________________
15 0.07 1.5 1.5 0.011 0.02 0.30 0.61 tr 100 45 5 17 10 2 5 3 13 29
16 0.01 0.5 1.5 0.003 0.02 tr tr tr 500 45 3 16 10 3 5 4 14 29 17
0.05 0.5 1.1 0.003 0.01 tr tr tr 367 45 3 16 10 3 5 4 14 29 18 0.03
0.1 1.4 0.005 0.01 0.2 0.85 tr 280 45 5 17 10 2 5 3 13 29 19 0.05
0.5 1.0 0.003 0.01 tr tr 0.05 333 45 3 16 10 3 5 4 14 29 20 0.05
0.1 1.9 0.007 0.01 0.2 0.59 0.05 271 48 5 18 8 4 2 3 12 30 21 0.005
0.1 2.5 0.007 0.01 tr 0.85 0.05 357 40 2 12 14 2 12 4 14 31 22 0.03
0.1 1.4 0.005 0.01 0.2 0.85 0.01 280 45 5 17 10 2 5 3 13 29 23 0.03
1.1 2.1 0.005 0.02 1.20 tr 0.01 420 45 3 16 10 3 5 4 14 29 24 0.03
0.3 1.1 0.003 0.25 0.40 0.95 0.10 367 45 3 16 10 3 5 4 14 29 25
0.01 0.2 1.8 0.003 0.01 tr 1.2 0.05 600 40 -- 25 12 1 9 3 10 32 26
0.01 0.4 2.4 0.003 0.01 1.1 0.9 0.05 800 54 5 2 5 2 2 3 27 32 27
0.05 0.1 1.5 0.007 0.01 0.2 0.59 0.13 214 45 3 16 10 3 5 4 14 29
__________________________________________________________________________
TABLE 5 ______________________________________ Varestraint Test
Strain (%) No. 4 10 15 ______________________________________ 15
YES YES YES 16 NO NO NO 17 NO YES YES 18 YES YES YES 19 NO NO NO 20
NO NO NO 21 NO NO NO 22 NO NO NO 23 NO NO NO 24 NO NO NO 25 NO NO
NO 26 NO NO NO 27 NO YES YES
______________________________________
* * * * *